Thankyou both. I've sorted that now. However - next problem: have tried using my Janome darning foot, which worked OK on my Featherweight, but on the 201 it's sitting too tightly on my quilt sandwich, which won't move freely. Of course a darning foot isn't among those I got with the 201...
I've just googled it, and people seem to be using modern ones successfully. Are you using an original one or a modern one?